Bn-4 heater step by step

[CarlSpackler]

I'd like to get some feedback on the cycle times for the various "phases" of a functioning heater. I ran mine through about a dozen cycles last night and these are average times per "phase" of a cycle:

1 Cold start up (fuel getting to heater) - 30 seconds
2 Burner runs but sounds weak and kicks on and off, pump continues - 45 seconds
3 Burner runs constantly and sounds like a jet plane - 50 seconds
4 Pump shuts off while fan continues - 50 seconds
5 Warm start up (once heater cools enough to restart burner) - 4 seconds
Return to #2

This is all with the heat control knob fully extended. About 40 degrees in the garage with the door open. Car stationary. #3 leads me to believe the glow plug is taking a while to get hot enough to get to #4. Or is this just how it's supposed to work? Car was nice and warm!
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'67 Micro Bus
'73 Thing
'91 Westy

[Bashr52]

I have posted this before but I wanted to capture is here since this is the unofficial official BN4 thread.

When I did my install my switch was busted all to hell. I bypassed the timer and went direct to a rocker switch, with the heater controlled just through the temp switch. Blower is still wired to direct power so to shut the blower down I just push the temp switch in and shut off the rocker. The blower continues to blow as normal until the cool down cycle is complete.

As others have mentioned my pump was seized up, so I just wired it direct to battery and started cycling the ground wire until the pump finally freed itself up and worked as normal.

The heater did not work correctly at first, so I took it all apart and replaced/updated the resistors and cleaned/tested all the switches and contacts. Worked perfect once reinstalled.

[vwwestyman]

Hmm, I asked about the noisy bearings a long time ago, and it appears that the last post in this thread was maybe addressing that.

Well it stayed quiet for a long time, but has gotten pretty noisy again. It has been 3 years since I've had the heater apart, so I'm not quire sure what part of the motor is showing in that pic/how much it was disassembled.

I've wondered if the bearings can be replaced? Anyone know? Also wonder if the Loctite 271 fixed it?
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Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[perello]

I found that my noisy BN4 had a wobbling bearing. I guess the correct thing would be to dismantle the motor, but I try using Loctite 271 to fix the bearing.

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Aug '58 pressed bumper SO23
1974 German Thing
1978 Bug 1200

[Der Speed Shack]

This info is great, but just for shits and giggles, is there anyone who does this as a service?

[hubscaps]

Thank you for the advice. I did the same process when I opened the new pump to prime and test it. Last night I removed the fan motor, cleaned the points and adjusted them. Once reassembled it worked like a champ! Today will be the first live test run so we will see how that goes. I will try and post a video for fun. Thanks for all the advice and support from the community

[vwwestyman]

If you want to see if it'll run, you can manually click the pump. I had a jumper wire from the wire that goes to the points. I had one end pushed in the connector, and tapped the other end to a ground at the approximate rate of three times per second.

The heater fired up, and I kept going. After a few minutes, the pump started running on its own and has since.

I had just put it back together from cleaning the points and such, so I don't know why they didn't work initially but that is how it went for me.

All that to say, perhaps you can jump start your points into working.
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Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[hubscaps]

Thank you so very much!! This diagram is a perfect match for my BN4 heater. Turns out I had the black & yellow wires swapped with the red wire on the flame switch. I swapped them over and now we are in business!

The last issue I have is the fuel pump points in the fan motor. They seem to not be working. I will open that up and check it out soon.

Thanks again for the help. I was at a loss until you sent me that link

[ente_kaefer]

[hubscaps]

Good day!

I am rebuilding a Eberspacher BN4 gas heater but I'm having a problem trouble shooting some wiring issues.

I have taken a picture of the data plate on the heater and a shot of the wiring and attached to this email for your reference.

I was wondering if you hade a copy of the correct wiring digram for my heater? Please note that my heater does not have a temperature control sensor at the exit of the heater.

Thank you in advance for any help you can offer.

[vwwestyman]

Wheeler Dealer guy could probably have saved $100 if he tried to free up the fuel pump. Oh well.

There was a thread somewhere about spreading out the heat from the outlet so you don't end up with a burned foot.

I used this pipe I had in the garage. I am pretty sure it is a generic intake hose kit from a FLAPS that I had leftover from a different project.

I did find that the rubber collar gets soft when warm and will fall off. A couple zip-ties seems to have cured that. I had another, more flexible air hose that I used to extend this. But the FLAPS one is a little harder and will generally stay in whatever position you flex it to. You can see the flexible hose shoved on to the end, that lets heat get to the back seat area.

Now I need to work on the radio wiring to see if it'll fire up!
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Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[kenj06]

notchboy,
that is what actually inspired me to get my BN4 running.

Saved myself some money by knocking on the fuel pump to get it working and repaired my thermostat
http://www.thesamba.com/vw/forum/viewtopic.php?p=6956473

For anyone working on the BN4 be sure to check the sticky:
http://www.thesamba.com/vw/forum/viewtopic.php?t=332848
priceless info here

[notchboy]

Link

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[vwwestyman]

Got the heater back in the Thing!

I ended up using white grease on the gear, and some silicone lube on the rubbing block for the other points. I attempted to dribble some silicone down into the motor bearings by the shaft though I don't know how much really made it down in there.

Since I couldn't easily find the info in the thread, I'll say that the point gap I used on both ends was .018. I used a metal nail file to clean them up, and hosed the whole area down with contact cleaner before lubing.

When I first tried to fire it up, the pump still didn't run. But just to see if it would fire up anyway, I clipped a jumper wire from the wire that is controlled by the points, and grounded it at roughly 3/second as I saw was the rate.

The heater fired up pretty quickly doing that. After a couple minutes, I quit manually working the pump and it was going on its own. I have no idea what the initial problem was, but that worked.

I let it sit there and run for a while, and the thermostat was cutting the pump in and out properly and all that. Also it times out after the heater is switched off properly.

I still have no windows or roof, but having some heat will take a little edge off during the mornings for now.
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[Pbotsonis]

[ente_kaefer]

Great thread !! I am going to assume I will be referring to it once I can locate a complete BN4 to install into my 1973 Thing . . .

[vwwestyman]

I have my heater torn apart. I followed the flowsheet to determine that the fuel pump wasn't receiving the signal from the points.

Got it all apart to reveal the points on both ends of the fan. Both were pretty dirty, a little corroded, and there is a lot of very fine dust inside the caps!

I was just curious about the best way to clean all that up? (I'm thinking contact cleaner should do fine.)

Also, what would be best to lube up the gear for the fuel pump points?

And while I'm in there, can I somehow lube the bearings of the fan? When I initially got it to run, it was making some bad noises but it quieted down. It sounds much better but is still a little noisy.
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Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[dekdiver]

I hope this post is still being looked at. There is some great information here. I do have some problems that I am not seeing an answer to.

For the most part, I don't have any problems getting my heater going. However, if my temperature nob is pulled out too far, my safety switch will trip. I have also noticed that it tends to trip more often these days even if I don't have the temp nob pulled out too far.

Has anybody experienced this and can I make any adjustments or clean something to keep this from happening?

Thanks

[Wildthings]

Heat worked, I couldn't find my little Butane torch so I used the oxy-act rig with the smallest tip I have. Made a heat shield that fit between the impeller and the housing and gave it a few seconds of heat against the hub. Came free very easy.

What someone needs to do is come up with an electronic pulse generator for both the pump and ignition points. They electronics could just sit up under a cover on top of the unit with all the rest of the controls so would be easy to access. I wonder what is used on newer heaters?

[man130]

I guess soak and heat as you suggested, if that fails I guess your gonna have to drill out the allen bolt and if you must maybe tap one size bigger if you mess up the threads drilling it out good luck